"Never before has a president personally intervened at the 11th hour, exercising political power at the expense of the law and science, to force EPA to accept weaker air quality standards than the agency chief's expert scientific judgment had led him to adopt," said John Walke, clean air director at the Natural Resources Defense Council, a private advocacy group. "It is unprecedented and an unlawful act of political interference."

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WASHINGTON (AP) -- The Environmental Protection Agency agreed to weaken an important part of its new smog requirements after being told at the last minute that President Bush preferred a less stringent approach, according to government documents.They show tense exchanges between the EPA and the White House Office of Management and Budget in the days before the smog air quality standard was announced Wednesday.

Changes directed by the White House were made only hours before the agency issued the regulation. The late activity forced the EPA to delay the announcement for five hours.

The disagreement concerned the amount of protection from ozone, or smog, that should be afforded wildlife, farmlands, parks and open spaces.

This "public welfare" or "secondary" smog standard is separate from a decision to tighten the smog requirements for human health, which the EPA decided to do by reducing the allowable concentrations of ozone in the air from 80 parts per billion to 75 parts per billion.

The revised human health standard has gotten all the attention. But the most contentious fighting involved the public welfare standard, according to papers inserted in the EPA regulatory docket Thursday.

The memos and documents indicate that EPA officials had wanted to make the public welfare standard more stringent than the health standard, although still not as protective as some scientists had recommended.

But the White House insisted on making both standards identical, according to the documents. When EPA officials balked, the issue went to Bush, who sided with his budget office.

The White House defended Bush's action.

"This is not a weakening of regs (regulations) or standards," White House deputy press secretary Tony Fratto said Friday. "But it was an effort to make the standards consistent. There's no question we have an interest in how federal regs impact communities."

Fratto said the new standards are the "most stringent smog standards in history" and that communities will have a hard time meeting them. He described the area where Bush intervened as 'a technical matter' and said he acted on the advice of the Justice Department.

The White House's involvement was first reported by The Washington Post.

Susan Dudley, head of OMB's Information and Regulatory Affairs, alluded to Bush's involvement in a last- minute memo to EPA chief Stephen Johnson.

"The president has concluded that consistent with administration policy, added protection should be afford to public welfare by strengthening the secondary ozone standard and setting it to be identical to the new primary standard," she wrote. It should not be weaker or more stronger than the human health standard, the OMB insisted.

Although the memo was dated Thursday, it was faxed to the EPA on Wednesday, hours before the agency announced the rule. Parts of the memo were included in the rule's preamble posted on the EPA Web site.

"Never before has a president personally intervened at the 11th hour, exercising political power at the expense of the law and science, to force EPA to accept weaker air quality standards than the agency chief's expert scientific judgment had led him to adopt," said John Walke, clean air director at the Natural Resources Defense Council, a private advocacy group. "It is unprecedented and an unlawful act of political interference."

Dudley, in a March 6 memo, had questioned the EPA's justification for have a stronger smog requirement for public welfare than for human health.

The "public welfare" -- or secondary -- standard is fashioned in a way to protect against long-term harm to the environment. The limits on ozone under this standard are likely to have more impact on rural areas than urban centers.

Environmentalists and ecologists have argued that the standard should be more stringent than the human health ozone standard.

Last year the EPA staff and a scientific advisory panel on clean air concluded that protection of forests, agricultural lands and the ecosystem requires a "substantially different" ozone standard from the one for protecting human health.

In recent weeks the Agriculture Department has weighed in against making the public welfare ozone standard tougher. The department expressed concerns about the impact additional pollution controls might have on agriculture and development of biofuels, especially ethanol.

The department made its concerns known to OMB. EPA officials said the need was clear for a different standard for public welfare and that drifting ozone pollution has been found to cause "adverse effects" on agricultural crops, forests and vegetation. E-mail to a friend E-mail to a friend

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